1. Field of the Invention
The present invention relates generally to a character input device, and, more particularly, to a character input device for a mobile device or a wearable terminal, which does not require the use of a keyboard.
2. Description of the Related Art
Generally, ‘radar’, which is an abbreviation for ‘RAdio Detection And Ranging’, is a system that was developed during World War II and has been used as auxiliary equipment for Air Traffic Control (ATC) and aircraft precision approach. Radar has been installed in airports by the U.S. Federal Aviation Administration (FAA) since the end of the 1940s, and has become major equipment for ATC nowadays.
Radar has an operating principle in which, when radio energy (a short pulse) is emitted from a directional antenna and collides against a target object, waves are reflected, that is, part of the energy returns, and the direction of the target object can be detected using a device for receiving and detecting a reflected waves. That is, radar is equipment for transmitting a radio wave to a target object, receiving the reflected waves of the energy of the radio waves, and measuring the position (direction and distance) of the target object using the round-trip time and the directional characteristics of an antenna based on the straightness and isochronism of a radio wave. Therefore, in the omni-directional emission/reception of a radio wave from/through a ground antenna, the time required for emission/reception is proportional to distance, so that the position of a target object and the distance to the target object can be detected using the direction to the target object. This has been used for the operating principle of distance measurement equipment.
With the development of System On a Chip (SOC) technology, radar devices have become ultra small and use low power. Therefore, bio radar devices for sensing the pulse and breath of humans have been commercialized, and radar devices can be applied to mobile devices.
A keyboard is an input device through which a user can input commands and data into a computer. When characters to be used in a computer are defined in the ROM of a keyboard and a user presses a key, the keyboard transmits the value of the corresponding key to the computer. The keyboard is classified as a QWERTY keyboard or a Dvorak keyboard based on the arrangement of input keys. The QWERTY keyboard is the most commonly used keyboard, and takes its name from the first six letters seen in the keyboard's top first row of letters, that is, ‘Q, W, E, R, T, and Y’.
FIG. 1 is a view showing the construction of a keyboard 100 used for a general computer 101 and a connection 102 between the keyboard 100 and the computer 101. The conventional keyboard 100 is manufactured on the basis of the desktop computer 101, so that the keyboard 100 includes at least 80 keys. Therefore, there are problems in that the keyboard is large and inconvenient to carry. As shown in FIG. 1, the conventional character input device 100 includes a keyboard for receiving characters from a user 103, and a microprocessor 104 provided inside the keyboard to sense a character input by the hand of the user and transmit information about the character to the computer 101. The information about a character is transmitted to the computer 101 in a Universal Serial Bus (USB) or Personal System 2 (PS/2) manner (refer to reference numeral 105). The PS/2 or USB port of the computer, which has received the information about the character, generates an interrupt whenever data is received from the keyboard 100, and informs the computer 101 of the presence of input information. The above-described character input device 100 is suitable for a fixed computer environment. However, when the character input device 100 is applied to a mobile device or a wearable device, which requires the user 103 to perform an input operation while moving, there is a disadvantage in that the usefulness of the character input device 100 is decreased by the low portability of the character input device. Further, there is a disadvantage in that the portability of the character input device is decreased because a user must always carry a character input device 100.
In order to overcome the above-described problems, various character input devices have been developed. FIG. 2 is a view showing an input device according to a prior invention.
Referring to FIG. 2, in order to solve the problem of the poor portability of the existing character input device, Korean Unexamined Patent Publication No. 10-2003-0092175 (entitled “Portable Keyboard”) discloses a portable keyboard 200, which substitutes a small number of keys for the existing keys, thereby being easily carried, and which is integrated with a mouse, thereby enabling an input operation to be performed with one hand. However, there are disadvantages in that a user must always hold the character input device 200, so that the degree of freedom of the hand holding the character input device deteriorates, and a large amount of learning is required to learn the input method of the corresponding keyboard 200.
Further, in order to solve the problems of the portability and usefulness of a keyboard, Korean Unexamined Patent Publication No. 10-2007-0036458 (entitled “Data Input Device using Gloves”) and Korean Unexamined Patent Publication No. 10-2003-0039648 (entitled “Wearable Glove-type Character Input Device”) disclose gloves that are configured such that, when a terminal, such as a mobile device or a wearable device, is used, a user wears a glove-type key input device 201 having a plurality of contacts, instead of using a keyboard mounted in a device, and inputs data required to execute a program via a wired/wireless connection 202. However, there is a disadvantage in that it is bothersome to input characters because a user must put on the gloves 201 in order to input characters, and there is a defect in that the degree of freedom of both hands deteriorates because sensors 203 are attached to the joints of fingers and both hands are connected via a wired connection 204.